低渗透油藏CO非混相驱前缘移动规律研究

Law of CO Immiscible Front Movement in Low-permeability Oil Reservoir

孟凡坤 雷群 苏玉亮 何东博

MENGFankun LEIQun SUYuliang HEDongbo

中国石油勘探开发研究院, 北京 海淀 100083 中国石油大学(华东)石油工程学院, 山东 青岛 266580

PetroChina Research Institute of Petroleum Exploration & Development, Haidian, Beijing 100083, China School of Petroleum Engineering, China University of Petroleum(East China), Qingdao, Shandong 266580, China

低渗透油藏CO非混相驱不同流体间相互作用复杂，前缘描述困难。为此，基于改进的CO驱相对渗透率模型，并考虑CO在原油中溶解及油相启动压力梯度的影响，推导出低渗透油藏CO驱分流量方程；引入渗流阻滞系数，对B-L方程进行修正，确立CO驱替前缘移动速度及饱和度剖面计算方法。通过与CO驱实验数据获取的含气饱和度剖面相对比，验证了计算方法的准确性。分析CO溶解作用、不同原油黏度及注入压力对CO驱前缘移动规律的影响，结果表明，考虑CO在原油中的溶解，前缘移动速度降低幅度超过50%；原油黏度越高，前缘移动速度越大；前缘移动速度随注入压力的增大而减小，并在最小混相压力处出现拐点。针对吉林、胜利与延长油田典型CO驱试验区，通过对比3者含气饱和度剖面分布，对3个区块CO驱的适应性进行了评价。

The interaction of different fluids in carbon dioxide (CO) immiscible flooding in a low-permeability oil reservoir is complex, and the description of the front is difficult. Therefore, the fractional flow model for the CO immiscible flooding in a low-permeability oil reservoir was derived herein based on an improved relative permeability model for CO flooding, considering the CO dissolution in crude oil and the influence of the pressure gradient of the oil phase. The computing method of the front movement speed of CO flooding and the saturation profile was established by introducing the seepage retardation factor to correct the B-L equation. The veracity of this computing method was verified by comparing with the gas saturation profile obtained from the CO flooding empirical data. The CO dissolution, viscosity of different crude oils, and influence of the injection pressure on the front movement speed of CO flooding were analyzed. The results indicated that the front movement speed was reduced by more than 50% considering the CO dissolution in crude oil. Moreover, the higher the crudeoil viscosity, the greater the front movement speed. The front movement speed decreased with the increase in the injection pressure and inflected at the point of minimum miscible pressure. The adaptability of the CO flooding of three typical test sites in the Jilin, Shengli, and Yanchang oil fields was evaluated by comparing the distributions of their gas saturation profile.

10.11885/j.issn.1674-5086.2017.02.28.06